Water Relations, Growth, and Dry Matter Accumulation of Sorghum Under Post-Rainy Season Conditions 1

Field studies were conducted on deep vertisols to assess the effects of water stress on the growth and DM accumulation of sorghum. Leaf water potential and stomatal conductance were measured diurnally on 4 dates during the growing season. Irrigated sorghum exhibited higher stomatal conductance, higher leaf water potentials, higher LAI and greater DM accumulation than non-irrigated sorghum. Higher transpiration rates in irrigated sorghum were explained by increased net radiation measured over the irrigated canopy. Lower leaves in the sorghum canopy showed lower stomatal conductance. Non-irrigated sorghum had fewer tertiary branches/secondary branch, fewer seeds/panicle and smaller seeds. Non-irrigated sorghum used 213 mm water to produce 0.51 kg DM/m2; irrigated sorghum extracted 321 mm water to produce 0.93 kg DM/m2